Avalanche Forecast

Decreasing winds and mostly light snow showers should be seen at Mt Hood on Saturday with much lower snow levels and much cooler temperatures. Not a lot of snow is expected following the front Friday but we will see how it goes. The avalanche danger should decrease on Saturday but the decrease will be a moving target and careful snowpack evaluation and cautious routefinding will be essential.

Layers of recent or new wind and storm slab may need a day to mostly stabilize. Water may also need a day to drain from the upper snow pack below about 4000 feet.

Recent moderate to strong southwest to west winds will make wind slab most likely on northwest to southeast slopes but keep an eye out on all aspects in areas of more complex terrain. Watch for firmer wind transported snow from Friday and possible deeper wind transported layers such as from Tuesday.

New storm slab formed on Friday evening may need a day to mostly stabilize on Saturday. Storm slab is most likely in area that experienced more than a few hours of rapidly accumulating snow.

Cornices won't be listed as an avalanche problem in this area but avoid areas on ridges and mountain tops were a cornice might be present and avoid slopes below cornices.

Weather and Snowpack

The most recent wet warm storm arrived on Valentines Day 2/14 and formed the uppermost very strong rain crust in our snowpack. 

A stronger than forecast storm late Monday through Tuesday deposited 2 - 2.5 ft of snow by Tuesday evening. The heavy snowfall arrived with very strong westerly alpine winds which gradually decreased on Wednesday.

Thursday began mostly sunny but increasing clouds were seen in the afternoon. SW winds above treeline increased and become were very strong Thursday afternoon, with a gust above 100 mph at 6 PM recorded at the Cascade Express weather station at Mt. Hood Meadows.

Strong southwest flow is carrying a strong front across the Northwest on Friday evening. At Mt Hood this will be causing strong southwest alpine winds, heavy, moist, dense new snow above about 4000 ft and wet snow or rain below about 4000 ft.

Recent Observations

Several contacts were made with the Mt Hood Meadows patrol through the day Tuesday and they reported widespread natural and triggered wind and storm slabs especially near and above treeline. Avalanches were occurring even on relatively low angled terrain. Low visibility limited additional observations but by Tuesday afternoon large hard wind slabs were developing above treeline and several sympathetic avalanches were triggered. The recent relatively stable snowpack had quickly turned into very dangerous avalanche conditions.

By Wednesday conditions had improved and the Mt Hood Meadows patrol reported sunny but windy conditions with windward slopes getting scoured and local size-able wind slab building on lee slopes. The lower mountain was showing signs of spring with rollerballs and small triggered loose wet avalanches.

On Thursday NWAC observer Laura Green reported that a sun crust had formed on solar slopes. She passed along that several natural hard wind slab avalanches had occurred in White River Canyon above treeline on E-NE aspects with crown depths up to several feet. She also saw a 2-4 ft crown in Newton Canyon on a NE slope at about 6400 ft. These hard slab wind avalanches likely occurred on Wednesday.

Laura was out in Heather Canyon on Friday morning and found a reactive wind slab layer giving moderate RP results at about 25-28 cm down in a pit on a NE slope at about 6450 ft. She was out later Friday on a tour in the East Fork area from 3500-5800 ft and found that the reactive wind slab layer was persisting there as well on a wind loaded slope about 25 cm down. Loose wet snow and pinwheels were seen below about 4000 ft.